Silicon-germanium alloys is one of the best thermoelectric materials in power generation devices operating
in 600-1000 C range in heat conversion into electricity directly. The enhancement of efficiency comes
mainly from a significant reduction in the thermal conductivity caused by the enhanced phonon scattering
off the increased density of nanograin boundaries.
When you are citing the document, use the following link http://essuir.sumdu.edu.ua/handle/123456789/3551

Karpenkov, D.U.

Khovaylo, V.V.

Korotitsky, A.V.

Maradudina, O.N.,

Usenko, A.A.

Voronin, A.I.

Electronic Sumy State University Institutional Repository

PROCEEDINGS OF THE INTERNATIONAL CONFERENCE  NANOMATERIALS: APPLICATIONS AND PROPERTIES Vol. 2 No 4, 04NEA13(2pp) (2013)   2304-1862/2013/2(4)04NEA13(2) 04NEA13-1  2013 Sumy State University Thermoelectric Properties of Si-Ge Nanostructured Thermoelectric Materials Synthesized by Mechanical Alloying  A.I. Voronin1, A.A. Usenko1, A.V. Korotitsky1, D.U. Karpenkov2, O.N. Soklakova3, V.V. Khovaylo1  1 National University of Science and Technology "MISIS", 4, Leninskiy Ave., 119049 Moscow, Russia 2 Tver State University, 33, Zhelyabova st., 170100 Tver, Russia 3 Belgorod State National Research University, 85, Pobedy St., 308015 Belgorod, Russia  (Received 18 June 2013; published online 31 August 2013)  Silicon-germanium alloys is  one of the best thermoelectric materials in power generation devices oper-ating in 600-1000 C range in heat conversion into electricity directly. The enhancement of efficiency comes mainly from a significant reduction in the thermal conductivity caused by the enhanced phonon scattering off the increased density of nanograin boundaries.   Keywords: Thermoelectric materials, Silicon, Germanium, Nanostructured, Mechanical alloying.   PACS numbers: 72.15.Jf, 73.50.Lw   1. INTRODUCTION  Today there is a great need for high-temperature and medium-temperature thermoelectric materials. This gap may well take a silicon germanium, which lends itself well to modification by nanostructuring. Bulk nanocrystalline thermoelectrics are the most promising materials for commercial applications. This is due to two reasons: 1) the relative cheapness of their production as compared to the creation of nanostructures in the form of quantum wells, quantum wires, and quantum dots and other methods which are far from commercialization, 2) experimental and theoretical results that demonstrate the possibility of increasing the thermoelectric figure of merit in bulk nanocrystalline materials by 20 percent or more as compared to the crystalline material [1]. This method is recognized as the easiest and most efficient at the time. A lot of published papers show the significant increase of thermoelectric figure of merit, but don’t tell a word about the methods and modes of its receipt [2]. This work presents studies of the structure of powders based on Si-Ge received with different parameters of mechanical alloying that allow one to get nano crystaline solid solution, as well as the alternative method for nanostructured material from the pre-alloyed samples, thus reducing the time of mechanosynthesis in the mill, and reduces contamination of the material [3]. It is shown in the present work that under optimum conditions of milling it is possible to get the nanoparticles with an average size of about 100 nm. Thermal properties were measured by a laser flash analysis method, Seebeck coefficient was measured by a static dc method and electric resistance was measured by a four-terminal method.  2. EXPERIMENT  The nanoparticles were prepared via techniques that include high energy ball milling under argon atmosphere of the pure elements. The nanostructure of the materials is confirmed by powder X-ray diffraction and transmis-sion electron microscopy. Fig. 1 illustrates the appear-ance of the material after milling. The average particle size is 100 – 200 nm.    Fig. 1 – TEM Microphotograph of Si-Ge nanopowder after milling  Nanoparticles were compacted in thermal and me-chanical testing systems Gleeble® 3800. Samples had the form of cylinders. Diameter of the samples was 12.7 mm. After the compacting process Seebeck coeffi-cient and thermal properties of the samples were meas-ured. Fig. 2 illustrates the dependence of the Seebeck coefficient on temperature. The data indicate that the compacting of nanoparticles leads to a significant in-crease in the thermoelectric characteristics of the mate-rial.    Fig. 2 – Seebeck coefficient of Si-Ge    A.I. VORONIN, A.A. USENKO, A.V. KOROTITSKY, ET AL. PROC. NAP 2, 04NEA13 (2013)   04NEA13-2 Thermal properties were measured by LFA 457. The thermal diffusivity reached the minimum value 0.812 mm2/sec at 700C.  3. CONCLUSIONS   Enhanced thermoelectric properties have been achieved in nanostructured dense bulk SiGe alloy. Appli-cation of system Gleeble® 3800 allowed us to receive samples of bulk nanostructured thermoelectric material, which allowed achieving a good thermoelectric parame-ters. The thermal conductivity reduction is mainly due to an enhanced phonon scattering at the increased bounda-ries of the nanograins.   REFERENCES  1. X.W. Wang et al., Appl. Phys. Lett. 361, (2008). 2. G. Joshi, X. Yan, H. Wang et al., Adv. Energy Mater. (2009). 3. A.A. Usenko, A.I. Voronin, A.V. Korotitsky, D.U. Karpenkov, O.N. Maradudina, V.V. Khovaylo, Herald of Chelyabinsk State University. Physics No16, (2013).  

Thermoelectric Properties of Si-Ge Nanostructured Thermoelectric Materials Synthesized by Mechanical Alloying

SocioEconomic Challenges Journal (Sumy State University)

PROCEEDINGS OF THE INTERNATIONAL CONFERENCE  
NANOMATERIALS: APPLICATIONS AND PROPERTIES 
Vol. 2 No 4, 04NEA13(2pp) (2013) 
 
 
2304-1862/2013/2(4)04NEA13(2) 04NEA13-1  2013 Sumy State University 
Thermoelectric Properties of Si-Ge Nanostructured Thermoelectric Materials Synthesized 
by Mechanical Alloying 
 
A.I. Voronin1, A.A. Usenko1, A.V. Korotitsky1, D.U. Karpenkov2, O.N. Soklakova3, V.V. Khovaylo1 
 
1 National University of Science and Technology "MISIS", 4, Leninskiy Ave., 119049 Moscow, Russia 
2 Tver State University, 33, Zhelyabova st., 170100 Tver, Russia 
3 Belgorod State National Research University, 85, Pobedy St., 308015 Belgorod, Russia 
 
(Received 18 June 2013; published online 31 August 2013) 
 
Silicon-germanium alloys is  one of the best thermoelectric materials in power generation devices oper-
ating in 600-1000 C range in heat conversion into electricity directly. The enhancement of efficiency comes 
mainly from a significant reduction in the thermal conductivity caused by the enhanced phonon scattering 
off the increased density of nanograin boundaries.  
 
Keywords: Thermoelectric materials, Silicon, Germanium, Nanostructured, Mechanical alloying. 
 
 PACS numbers: 72.15.Jf, 73.50.Lw 
 
 
1. INTRODUCTION 
 
Today there is a great need for high-temperature and 
medium-temperature thermoelectric materials. This gap 
may well take a silicon germanium, which lends itself well 
to modification by nanostructuring. Bulk nanocrystalline 
thermoelectrics are the most promising materials for 
commercial applications. This is due to two reasons: 1) the 
relative cheapness of their production as compared to the 
creation of nanostructures in the form of quantum wells, 
quantum wires, and quantum dots and other methods 
which are far from commercialization, 2) experimental 
and theoretical results that demonstrate the possibility of 
increasing the thermoelectric figure of merit in bulk 
nanocrystalline materials by 20 percent or more as 
compared to the crystalline material [1]. This method is 
recognized as the easiest and most efficient at the time. A 
lot of published papers show the significant increase of 
thermoelectric figure of merit, but don’t tell a word about 
the methods and modes of its receipt [2]. This work 
presents studies of the structure of powders based on Si-
Ge received with different parameters of mechanical 
alloying that allow one to get nano crystaline solid 
solution, as well as the alternative method for 
nanostructured material from the pre-alloyed samples, 
thus reducing the time of mechanosynthesis in the mill, 
and reduces contamination of the material [3]. It is shown 
in the present work that under optimum conditions of 
milling it is possible to get the nanoparticles with an 
average size of about 100 nm. Thermal properties were 
measured by a laser flash analysis method, Seebeck 
coefficient was measured by a static dc method and 
electric resistance was measured by a four-terminal 
method. 
 
2. EXPERIMENT 
 
The nanoparticles were prepared via techniques that 
include high energy ball milling under argon atmosphere 
of the pure elements. The nanostructure of the materials 
is confirmed by powder X-ray diffraction and transmis-
sion electron microscopy. Fig. 1 illustrates the appear-
ance of the material after milling. The average particle 
size is 100 – 200 nm. 
 
 
 
Fig. 1 – TEM Microphotograph of Si-Ge nanopowder after 
milling 
 
Nanoparticles were compacted in thermal and me-
chanical testing systems Gleeble® 3800. Samples had 
the form of cylinders. Diameter of the samples was 
12.7 mm. After the compacting process Seebeck coeffi-
cient and thermal properties of the samples were meas-
ured. Fig. 2 illustrates the dependence of the Seebeck 
coefficient on temperature. The data indicate that the 
compacting of nanoparticles leads to a significant in-
crease in the thermoelectric characteristics of the mate-
rial. 
 
 
 
Fig. 2 – Seebeck coefficient of Si-Ge  
 
 A.I. VORONIN, A.A. USENKO, A.V. KOROTITSKY, ET AL. PROC. NAP 2, 04NEA13 (2013) 
 
 
04NEA13-2 
Thermal properties were measured by LFA 457. The 
thermal diffusivity reached the minimum value 
0.812 mm2/sec at 700C. 
 
3. CONCLUSIONS  
 
Enhanced thermoelectric properties have been 
achieved in nanostructured dense bulk SiGe alloy. Appli-
cation of system Gleeble® 3800 allowed us to receive 
samples of bulk nanostructured thermoelectric material, 
which allowed achieving a good thermoelectric parame-
ters. The thermal conductivity reduction is mainly due to 
an enhanced phonon scattering at the increased bounda-
ries of the nanograins. 
 
 
REFERENCES 
 
1. X.W. Wang et al., Appl. Phys. Lett. 361, (2008). 
2. G. Joshi, X. Yan, H. Wang et al., Adv. Energy Mater. 
(2009). 
3. A.A. Usenko, A.I. Voronin, A.V. Korotitsky, 
D.U. Karpenkov, O.N. Maradudina, V.V. Khovaylo, Herald 
of Chelyabinsk State University. Physics No16, (2013). 
 


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Thermoelectric Properties of Si-Ge Nanostructured Thermoelectric Materials Synthesized by Mechanical Alloying

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